Tottenham are investigating a report of racist abuse towards South Korean forward Son Heung-min during the club's 1-0 defeat by Manchester United on Sunday.
Spurs, whose manager Mauricio Pochettino recently said he wanted to 'kill racism', are working with a season ticket holder who tweeted about the abuse mid-game.
Among a series of tweets detailing what happened, supporter James Dickens wrote: 'I've not experienced racism at football for about 15 years. But today at @SpursOfficial was hideous.
I've not experienced racism at football for about 15 years.